It had been believed that gene mutations in a protein called titin affect only people with dilated cardiomyopathy, one of the most common forms of inherited heart disease.

But this study of more than 1,400 adults found that the hearts of healthy people with mutations in this gene may be "primed to fail" if affected by other genetic or environmental factors. About 35 million people worldwide may be at risk, the researchers said.

"Our previous work showed that mutations in the titin gene are very common in people diagnosed with heart failure. Around 1 percent of the general population also carry these mutations, but until now it wasn't known if these are 'silent' gene changes or changes that can adversely affect the heart," said co-author Dr. Antonio de Marvao in a news release from Imperial College London. He is a clinical lecturer at the college's MRC Clinical Sciences Centre in England.

Study co-senior author Dr. Stuart Cook is a professor of cardiovascular medicine at SingHealth Duke-NUS Academic Medical Center in Singapore. He said, "We now know that the heart of a healthy individual with titin gene mutation lives in a compensated state and that the main heart pumping chamber is slightly bigger."

He said the next step is to identify the specific genetic or environmental triggers, such as alcohol or viral infection, that increase the risk of heart failure in people with titin mutations.

Dr. James Ware, clinical senior lecturer in genomic medicine at Imperial College London, said the findings could lead to new treatments.

"For patients with dilated cardiomyopathy, this study has improved our understanding of the disease, revealed possible new targets for drugs and other new therapies, and importantly has improved our ability to diagnose the condition confidently with genetic tests," he said in the news release.

The study was published Nov. 21 in the journal Nature Genetics.

More information

The U.S. National Heart, Lung, and Blood Institute has more on heart failure.